This invention relates to the manufacture of sand cores and molds for casting of metal products and particularly to a method and apparatus for production of cores and molds of widely differing specifications.
In the casting of a product, a core and/or mold is formed of sand and a binder to define a cavity in accordance with the desired product shape. The method and apparatus may be applicable to either a core or a mold and is described hereinafter with reference to a core for simplicity of description. For high quality casting processes, various binders and additives may be mixed with the sand prior to its introduction into the core box. Suitable activating materials or processes are then introduced to the sand mix at the core box to activate the binder within the sand core and thereby complete the casting of the sand core. In a production foundry, sand is mixed with appropriate binder and additive materials at one station and then distributed to the appropriate core box by a suitable distribution system. The recipe of materials is significant and equally important is accurate combining of the several components. For mass production processes, it is also important to maintain a continuous flow of material in a rapid and efficient manner.
The different casting processes may require different mixes of sand, binder and various additives. Although the batches for different products may use the same basic ingredients, the relative gerantiter will change. Further, different binders may be used. For example, sodium silicate gas and ISOCURE are two generic families of binders used in the sand mix for forming of cores and molds for sand casting. Certain sand casting mixes are activated by CO.sub.2 gas while others are set by DMEA gas. Additives are often required to produce the desired finish to the final casting to control the flow ability of the sand into the core box, the hardness of the core and the like. Sand coremaking is in fact a highly developed art. Although basic mixes are similar, a proper core mix is extremely complex with each factor critical to a final mix. Further, the particular mix is not directly subject to analytical determination but also includes much empirical information. The number of recipes for core mixes is therefore voluminous, and is often based on know-how and experience related to a particular casting process and product. As a result, the core making process has required much care and attention.
There is a need for an efficient and cost effective automated sand core forming process and apparatus which can be applied in the environment of a sand core forming operation.